Description & Characteristics. The ‘perlucidus’ cloud variety can be found amongst only two cloud types: altocumulus and stratocumulus. Translated from latin, meaning pellucid, the two types of perlucidus clouds are respectively abbreviated as ‘Ac la’ and ‘Sc la’. Perlucidus cloud formations can be easily identified as clouds with gaps in between cloud rolls or cloud heaps where you can see blue sky.
The perlucidus cloud variety is fairly common, especially amongst altocumulus clouds. Sometimes they take on an appearance that can be best described as cracks in a sidewalk. As a cloudspotter, if you see clouds that are perlucidus, you can work backwards to help you identify the cloud as altocumulus or stratocumulus. They’re commonly found alongside the stratiformis cloud species. If they’re thin enough, they can also classified alongside the translucidus cloud variety. Perlucidus clouds are very rarely found alongside the opacus and lacunosus varieties.
Try not to confuse the cloud varieties translucidus and perlucidus. As noted above, perlucidus clouds can be translucidus, but the two varieties can be differentiated by translucidus clouds are transparent, where perlucidus clouds are identified through the cloudless gaps in between the cloud heaps. Also note that translucidus clouds can be found altostratus and stratus clouds in addition to altocumulus and altostratus.